Orofacial pain disorders encompass a wide range of conditions including trigeminal neuralgia, reflex sympathetic dystrophy (RSD) of the face, temporomandibular joint disorders, periodontal pain, burning mouth syndrome, dental surgical pain, head and neck cancer pain, pain due to oral infections, and other neuropathic and inflammatory pain conditions. One common symptom in many chronic orofacial pain conditions is the severe painful sensation induced by cooling temperatures that would normally produce innocuous or pleasant cooling sensation. Unfortunately, the current clinical treatments are unsatisfactory for this chronic orofacial pain condition. This is largely due to the poor understanding of sensory coding mechanisms for cold stimuli in trigeminal sensory system. Several ion channels including TRPM8, TRPA1 and K2P have recently be proposed to be candidates of cold-sensing receptors. The overall goal of this proposal is to identify, in chronic orofacial pain conditions, I) Which of these cold-sensing receptor candidates are involved in innocuous cold- induced orofacial pain, and II) What peripheral and central neuronal mechanisms are responsible for the maintenance of chronic orofacial pain induced by innocuous cold. Advanced neurological techniques including patch-clamp records and calcium imaging together with other approaches including retrograde tracing, immunostaining and animal models will be used in this project. By accomplishing our goal, we will have identified novel therapeutic targets for treating some intractable orofacial pain conditions. PUBLIC HEALTH RELEVANCE Orofacial pain conditions are significant clinical problems that have not been treated satisfactorily due to the poor understanding of neuronal and molecular mechanisms. This project will use advanced neurobiological approaches and animal models to identify thermal receptors and neuronal mechanisms that are involved in an orofacial pain state induced by innocuous (non-painful) cold temperatures, a condition seen in patients with trigeminal neuropathy and other pathological disorders in orofacial regions. The accomplishment of the Aims proposed in this project will lead to novel therapeutic targets for treating some orofacial pain conditions.